Security codes such as a PIN (Personal Identification Number) and PUC (PIN Unlock Code) which may also be called a PUK (PIN Unlock Key) control the usability of a SIM (Subscriber Identity Module) of a mobile phone. The security codes (PUK and pre-set PIN) are delivered to a user in conjunction of a purchase of a subscriber connection. The PIN is a rather short code having usually only a few numbers (four for example). Every time the mobile phone is switched on, the mobile phone requires the user to input the PIN. After inputting the pre-set PIN, the user may freely change the PIN. If an incorrect PIN is typed more than a predetermined times (usually three) in response to the inquiry, a proper use of the mobile phone is blocked by locking the SIM and/or the mobile phone. The locked state can be unlocked by entering the PUC which is typically a much longer code than the PIN. The PUC cannot be changed by the user. If an incorrect PUC is typed more than a predetermined times (such as five), the use of the mobile phone is permanently blocked.
First mobile phones had one subscriber identity module (SIM) card. Since then the number of SIM cards has increased. A present mobile phone may have dual or triple SIM cards. Although a number of SIMs could bring many advantages, dealing with a plurality of SIMs and their security codes isn't simple. Also it may be difficult to remember even one security code. Additionally, to change a PIN may be challenging. Hence, if a mobile phone is lost or stolen, the unauthorized use of the mobile phone which depends on the security codes, may be too easy. Hence, there is a need for better solutions.